Integrated Bloch‐Siegert <i>B</i><sub>1</sub> mapping and multislice imaging of hyperpolarized <sup>13</sup>C pyruvate and bicarbonate in the heart
Bibliographic record
Abstract
Hyperpolarization of (13) C labeled substrates via dynamic nuclear polarization has been used as a method to noninvasively study real-time metabolic processes occurring in vivo. In these studies, proper calibration of radiofrequency transmit power is required to efficiently observe rapidly decaying magnetization. Conventional transmit radiofrequency field (B₁⁺) mapping methods rely on placing magnetization in a fixed, known state prior to imaging, making them unsuitable for imaging of hyperpolarized magnetization. Recently, a phase-based B(1) mapping method based on the Bloch-Siegert shift has been reported. This method uses a B(1) -dependent shift in the resonance frequency of nuclei in the presence of an off-resonance radiofrequency pulse. In this article, we investigate the feasibility of Bloch-Siegert B(1) mapping and observation of metabolism of hyperpolarized [1-¹³C] pyruvate in vivo, in a single injection. The technique is demonstrated with phantom experiments, and in normal rat and pigs in vivo. This method is anticipated to improve quantitative measurements of hyperpolarized (13) C metabolism in vivo by enabling accurate flip-angle corrections. This work demonstrates the use of Bloch-Siegert B(1) mapping under challenging out-of-equilibrium imaging conditions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".